Method for the detection of methyl chloride



Patented Apr. 30, i929.

UNITED STATES PATENT OFFlCE.

GEORGE S. LOBDELL, 01' ?OTBDAI, AND HENRY J. KAU'IH, noun, NEW YORK.

METHOD FOR THE DETECTION OF IETHYL CHLORIDE.

No Drawing. Application filed Key This invention relates to a method for the detection of methyl chloride as applied to refrigeration, particularly to the detection of leaks in a refrigerating system which employs a refrigerant whose essential ingredioil or a soap solution to t e ent'is methyl chloride.

An object of this invention is to provide a rapid, sensitive and dependable test.

In order to accomplish the result, according to this invention, many experiments have been made and it has been found that methyl nitrite added to the refrigerant fulfills the following exacting conditions:

1. It is non-corrosive when used in small quantities, especially in a water-free refrigerating system.

2. It is so sensitive to the action of certain reagents that it can be added to the refrigerant in quantities so small that it will not afiect the operation of the refrigerant but will be sufliciently large to give a sensitive test.

3. Its liquefying temperature is such that it is evenl distributed throughout all the phases of t e refrigerant.

A prime object of this invention is to provide a method for the detection of methyl chloride as applied to refrigeration for the reason that methyl chloride, because of its high efiiciency as a refrigerant. is much desired for this purpose, its onl disadvantage being itsgeneral inactivity w ich is characteristic of the 'al 1 halides. activity, locating cake in a refrigerating system has been a tedious and uncertain process. It is to remedy this condition that-the follow ing test has been developed.

11 operation, this invention provides a method for detecting leaks in a refrigerating system which employs a refrigerant whose essential ingredient is methyl chloride. The resent common method of detecting leaks in such systems is by the a plication of light suspected joint and the observation of bubbles formed y gas. This method is slow, difiicult to app y, and has the greater disadvantage that it is not capable of detecting small uantities of escaping gas. Int e ractice of this invention, ass or met 0d is as follows: Add to the methyl chloride of one per cent of methyl nitrite. However, it is not desired to confine this invention to a definite orpi b t e escapin' the proc- Due to this in- 2a, 1927, Serial No. 194,954.. lenewcd September 4, was.

proportion as herewith set forth since more or less may be used with no effect other than changmgthe speed and sensitivity of the test. The joint or ipe is then examined by placinga strip of a rbent paper moistened with a fresh y mixing equal parts of the following stoc solutions:

A. A solution made by dissolving 8 grams of sulfanilic acid to 1000 c. c. of 5 normal acetic acid.

B. A solution made by dissolving 5 grams of alpha-naphthylamine in 1000 c.. c. of 5 normal acetic acid.

Since the methyl chloride and meth l nitrite are at all times completely mixed, tlze formation of the characteristic pink color on the paper, which is a test for nitrite, must also show the presence of methyl chloride.

In making the experiments leading up to this discovery and invention, a well equipped .991 b. p.-l3 C.yields free nitrous acid in 86 the presence of certain reagents, non-poison- Basic for test.

A variable rtion of methyl nitrite is injected into t e system. The quantity of GH NO ma vary between wide limits but may be us 1n quantities as small as 1% of the volume of methyl chloride used.

' At any point in the system, the release of 1 1 be accompanied by a pr'oporalpha-naphthylamine acetate are required for the detection of CH,NO,. These solutions 1 shouldbe kept in separate stock bottles and mixed 1n equal proportions each day on which testing is to done. Testpaper should be prepared solution made by to CHfl-colorless gas, sp. 8o

(ll-can be detected by de- 1 absolutely ure and of chemical filter paper grade, pre erably made into rolls about one inch (1") wide. A short piece of the paper is wetted with ,the mixed solutions and wrapped once around the joint. Wetting the paper does not materiall affect its color, but the slightest trace of H NO produces a 'distinct red.

What we claim is- 1. A method for'the detection of methyl chloride in refrigerating systems using a refrigerant, comprising the addition of methyl 'nitrite to the refrigerant and the detection of the methyl nitrite through the use of one of its characteristic reactions consisting of the reaction with alpha-naphthylamine acetate and sulfanilic acid.

2. A method for the detection of leaks in refrigerating systems which employ a refrig erant whose essential ingredients is methyl chloride comprising the addition of approximately two-tenths of one per cent of methyl nitrite to the refrigerant, then testing the location. of the leak by placing a strip of absorbent paper'thereon, the paper being moistened with a liquid consisting of equal parts of a solution com rising 8 grams of sulfanilic 'acid dissolve in 1000 c. c. of 5 normal acetic acid, and a solution comprising 5 grams of alpha-naphthylamine dissolved in 1000 c. c. of 5 normal acetic acid.

3. A method for the detection of leaks in refrigerating systems employing a refrigerant whose essential ingredient is methyl chloride comprising the injection into the system of a variable portion of methyl nitrite, CH NO which may-be used in quantities as small as 1% of the volume of methyl chloride used, the system is then examined for leaks by placing a strip of absorbent paper moistened with a suitably prepared solution over the portion of the system being tested.

4. A method for detecting leakage in systems containing methyl chloride con'iprising adding methyl nitrite to the methyl chloride and detecting the presence of methyl nitrite at the point of leakage from the system by means of its reaction with a mixture of a suitable salt of alpha-naphthylamine and sulphanilic acid.

5. A method for detecting leakage from a system containing methyl chloride to which has been added methyl nitrite which comprises determining the prescene of the methyl nitrite at the point of leakage bv means of a characteristic color reaction.

In testimony whereof we aflix our signatures.

GEORGE S. LOBDELL. HENRY J. KAUTH. 

